Electrically-operated hoist.



E. L. STONE.

ELECTHICALLY OPERATED HOIST; APPLICATION mm SEPT. 14, 1914.

1,200,26L Patented Oct. 3, 1916.

Witnesses: Inventor:

2 2- aw E H i s Attorn e13 UNITED STATES PATENT OFFICE.

FRED L. STONE, OF

Specification of Letters Patent.

scHENEc'rAnv, NEW vomz fnssroivoa TO GENERAL ELECTRIC" COMPANY,AGORPORATION or NEW YORK. a

Patented Oct. 3, 1916.

Application f led September 14, 1914. Serial No. 861,504.

To all whom it may concern Be it known that I, FRED L. STONE, a subjectof the King of Great Britain, residing;

at Schenectady, county of Schenectady, State of New York, have inventedcertain new and useful Improvements in Electrically-Operated Hoists,of'which the following is a specification.

My invention relates to electrically operated hoists and has for itsobject the provision of means whereby the overwinding of the hoist dueto carelessness of the oper- V ator or other cause is prevented.

In the operation of hoisting machines, such, for instance, as m1n1ngholsts, the

' cages travel at a relatively high speed, and

it is therefore necessary that the motor be slowed down some time beforethe stopping point is reached in order to eflect a safe landing withoutover travel. For instance,

,if the operator should neglect to slow down his motor when the cagenears the limit of its upward travel it may be impossible to stop it atthe landing and it will therefore overtravel and may cause seriousdamage.

One of the objects of my invention 1s to provide means whereby in casethe operator fails to slow down at the proper time or at the properpoint in the operation of the hoist the motor circuit will beautomatically opened.

In carrying out my invention I provide two circuit controlling devicesfor control-' ling the motor, one controlled by the speed oi the motorand the other controlled by the position of the hoist. The arrangement-is such that the motor circuit can only be closed when the circuitcontrolling devices are in corresponding positions, that is, when thehoist is in a certain position, the motor must be at a certain speed,otherwise the motor circuit will be opened. In this way, when the cagereaches. certain positions at which the operator should slow down to acertain speed, if he does not slow down to this speed the motor circuitwill be opened, and the hoist will be automatically stopped.

Other objects and features of my invention will appear in the course ofthe following specification in which I have d1sclosed my invention.embodied in concrete form for purposes of illustration.

The accompanying drawing illustrates my invention applied to one form ofelectrically driven hoist.

its application to this particul'ar form of hoist. The two cages areindicated at C, C attached to two cables 0, 0 These cables wind andunwind from the drums D and D which are mounted upon the shaft S drivenby an electricmotor-M, which. is here illustrated as a three phaseinduction motor. Current is supplied to the motor by the three legs 1,2, 3 of a three phase supply. line, controlled by a switch 4,hererepresented as one which can be opened and closed by anelectromagnet 5 in a controlcircuit 6 supplied with current from mains7. The rotor of the motor is equipped'with collector rings 8- connectedto a resistor through switches in a receptacle 9 connected to acontroller 10, so that the operator withdrawn from the disk by a coil'13 in the control circuit 6 when control circuit is closed. A speedresponsive device 14, here represented as a fiyball governor, is gearedto the shaft, and actuates the movable contact of a switch, preferablyby means of a lever 15 fulcrumed at 16, and having one arm pivotallyengaged with the movable sleeve 17 of the speed governor. The other endof thelever is connected to two sliding contacts 18, 19, eachcooperating with its' also with a single contact 22,23, parallel withsaid segments. The movable contacts 18, 19 are mechanically, butnotelectri-. cally, connected, preferably by the rigid rod 24 on whichthey are mounted, butfrom which they are insulated. The contacts 22,

23, form part of the control circuit 6.

The shaft S carries two pinions which mesh with spur gears 25, 26secured to two long screws 27, 28, the former right hand and the latterleft hand. Engaged with each screw is a fleeting nut 29, 30, restrainedfrom rotation by guide rods 31, along which they can slide. Parallelwith the screws are the rods 32, 33, each attached to an insulatedcontact 34, 35 which cooperates with 'own set of insulated segments 20,21 and Q38 and are long' enoughtocover mentsin their respective banks;'fThe; rods; in'line with" the nuts 29, 30 re -g 32, 33' are 'abank ofinsulated segments' :The

I twocontacts' 34, 3.5 are-electrically connectond tm 3 all th s e-'3ed, for example, byathe flexible spective1y-,g so that they willbefstruc'l; by I said nuts when the latter travelto the .left "inthedrawing. Azweight 39 attached to -a faThe" operation cord connected toeachco'ntact 34:, 35 and running over a-pulley 4:1", brings the con-'tacts back-"to the right when the nuts-are backedaway l Thejsegments in;all four banks 20, 21,

36, 37,; are; equal in-fnumber, and those in banks'j20, 21, fnumberingfrom left to right,

are connected electrically by groups of .con-

ductors 42, 43' respectively, with corre vspending segments. in banks36, 37, numberin'g from right to left; the two groups of 'conducors' andtheir-- terminal segments forming portions of the control circuit, con-'nectedzun SGIIBS;

partsto stand as in-the drawing, and that the engineer starts tohoi'stthe cage C. The

motor acquires full speed veryquickly and' "maintains a uniform speeduntil near the end of the run, when theoperator-is sup-- posed to cutthe resistance into the rotorxcir-.- cuit and slow .it down to bring thecage safely and' accurately to the landing, J .wher e .it isstopped byopening and applying the brake ;As the motor acfull" speed, thegovernorballs'willfl and the the same rate that the contacts'18, 19 aredrawn-over the segments 20,21, thus keep 'ing the controll circuitGclof'sed. If the'engineer cuts in-his motor too rapidly, ithe'sipeedcontrolled contacts 18, i=9 will outrun the I cage controlled contact34: and the motor cir cnit'willbe opened at the switch t. Assumm hhoweyenn that this has not occurred, t e- Just here the nut 80, whichhas been travelthe bar: contact '35. speed governor, slowing-down withthe mos-f tor, begins to push the contacts l8 ,19 to the -=ing along itsscrew as the cage came up,

strikes the rod. 33' and begins to push back Simultaneously, the

right 'over'the segments 20, 2l atthe same speed as the contact 35,until, when'the cage C comes ,to the top, the-speed controlled is asfollowsi Assume the the ..motor circuit cage. will hehoisted rapidlyuntil, near fltheL-e'nd .ofitsrun, the engineer begins to f cut inresistance to slow down the motor.

but permits the speed. governor tohold the contacts- 18, 19 at the leftuntil afterthe nut 30 has begun slidingfthe contact 35 to the leftoverthe segments 37,: the control circuit.

will be broken at oneof 'thesesegmentszand the motor will be stopped-LSoytoo, if 1 the f engineer does not stop the: cage when .the'--.contact 35"is on the last .of the live. 'segments .37, the

stop the cage.

The drawing is wholly lillustrative does not attempt to show the partsin their proper proportions-or relations. .The screws v, a

order to shift the contacts 34, 35 over the eflif tire bank'ofsegme'nts36, 37 during the c0m-- 27, 28 will have to be ofa steep-pitch-incontact willfrun 'oif .on the vead segment,break thecontrol}circhit,'and

paratively short timein which the motor is accelerating andslowing down.In other words, the fleeting nuts will be travelin said screws comi intoservice onl at the I fidly forthe greaterpart of the length 0 outer endsof he ;screwsl*flf-necessary, the I movement of the could be multipliedby suitable means to-insurm a greater vand quicker travel: of.thecontacts 34,, 35, as will be readilyapparent to thelskilled engineer.It is also' evident-that if the s ystem is ap pliedtoa b61517 having butone cage, the

-. switches '2 ljand 35 ."andthe group of circuits 1 423 could bedispensed with; the bar 23 being:

connected directly; to. the contact 34;

\iIn-accordan'ce ?with the provisionsofthe patentjstatutes, I havedescribed the principle of operation of my invention, together with theapparatus which-I now consider to represent the bestembodimenttthere'of; but I desire toha tie it understood that theapparatus shown I is fonly illustrative, and that the invention can becarried out by other means. j

WhatI-claim as new and desire to secure by Letters Patent of theUnited-States, is

1. The combination/with the motor of an electric hoist, of; means forgradually varying'the speed ofsaidmotor between certainpoints in thetravel of the hoist,'comprising a controller, a speed responsive deviceactuatingthe same to various positions, a second controller actuated bythe hoist, and connections between the controllers for effecting thecontrol when the controllers arenot' in corresponding positions,

2. The combination with the motor of an electric hoist,'of means forautomatically controlling [said 3 motor comprising two cir- 'cuitcontrolling devicesconnfected in series in the motor control circuit andadapted during acceleration and deceleration of the hoistto assumecorresponding positions, one

controlled by the speed of the motor'and-the' switch will be in theposition illustrated, and other controlledbythe position of the cage g,the contacts 3%, 35 MB occupy positions the or number of revolutionsofmotor.

3. The combination with th'e "motor of an reverse of those shown If theengineer does not slow down the motor soon enough,

' electric hoist, of means for autonr1';n'sically cuit controllingdevices each having a p1u-.

rality of controlling positions, one of said devices being controlled bythe speed of the motor and the other controlled bye-the position of thecage or number of revolutions of motor, and connections whereby the twodevices must be in corresponding positions in order that the motorcircuit will be closed.

4. The combination with the motor of an electric hoist, of ,a controlcircuit therefor containing a group of parallel conductors, a switch atone end of said group controlled by a speed responsive device, and aswitch at the other end of said group controlled by] nected switchescooperating with the segthe movement of the cage. I

The combination with the motor of an electric hoist having twooppositely moving cages, of a control circuit therefor containing twogroups of parallel conductors said groups being connected in series,switches at the remote ends of said groups controlled simultaneously bya speed responsive device, and electrically connected switches at theadacent ends of said groups controlled re- 'spectivel by the cagedriving mechanisms.

6. Means for preventing the overwinding of an electric hoist,con'iprlsmg an electric control circuit for the motor, a plurality ofcircuits each terminating at each end in the cm'responding segment'ot'-a bank of segmeuts, a speed controlled switch connected to the controlcircuit and cooperating with one bank of segments, and a switchcooperating with the other bank and actuated by the hoist during thelatter part of its travel.

7. Means for preventing the overwinding v of an electric hoist drivingtwo winding drums, comprising an ele ric control circuit for the, motor.wvhich includes-.twc' groups ot parallel conductors each termini-tingat each cud in one of a bank of segments, two switches cooperating withthe segments'at one end of said groups, a speed responsive deviceoperatively connected to both switches, electrically connected switchescooperating with thesegments at the other end of said groups, andmechanism geared to each drum for operating itsrespective switch.

8. Means for preventing the overwinding of an electric hoist driving twocages, comprising an electric control circuit for the motor whichincludes two groups of parallel conductors each terminating at each endin one. of a bank of segments, two switches cooperating with thesegments atoneend of 'said groups, a speed responsive device operativelyconnected to both switches, conments' at the other end of said groups,and

mechanism geared to each cage for operat-' prising an electric controlcircuit for the motor including two. groups of parallel conductors eachterminating at each end in one of a bank of segments, two switches c061erating with the segments at one end of said groups, a speed responsivedevice operatively connected to both switches, connected switchescooperating with the segments. at the other end of said groups, andmechanism geared to each cage for operating its res ective switch duringthe upper portion 0 its travel only, both in hoisting and lowering,

and simultaneouslywith the movement of the speed controlled switches,

In witness whereof, I have hereunto-set my hand this 12th day ofSeptember, 1914.

BENJAMIN B. HULL, BENJ. H. WVEISBROD.

